This mudra is often used while sitting in a meditation and can be seen in countless statues of the buddha. I personally like to use this mudra as a little reminder of a few things. One being not to get too caught up in the dialog that is running through my head at any given moment (meditation included). It can be comical, if not a little frustrating, to come to see that I've been sitting on a cushion attempting to connect to that higher self or the Supreme Reality only to discover I've actually been talking with myself the entire 15 minutes. There is that blasted ego again! So thumb and index fingers together just to simply recall my intentions to step outside of my small self for a moment.
There is another way that I like to use this mudra and that is to serve as a reminder that I am not alone in this world and everything I do has an effect on someone else. Embodying this understanding means offering love and kindness to all others- even people I don't like or don't know. It is becoming more and more relevant and important for me to attempt to see myself in others simply because doing so breaks down barriers. So thumb and index fingers together to serve as a nudge in the direction of non-judgement and compassion.
All love in compassion
All compassion in understanding
All understanding in letting go
All letting go in love